Treatment of wood to extend serviceable life (preservation) has many applications. Treated wood is used in fence posts, utility poles, residential and commercial decking, railroad ties and the like. Additionally, woods that can be treated range from soft woods, such as for example pine, to hard woods such as for example oak or maple.
Methods used to treat wood can be energy and labor intensive. Presently, wood treatment of only sapwood can require subjecting wood to vacuum, followed by high pressure to impregnate wood with treatment compositions. Pressures in the range of 50-250 psig can be used for preservation of wood. Typically, the use of high pressure for wood treatment requires costly pressure containment vessels, controllers and pumps. Associated maintenance costs of those pressure containment vessels and pumps can be high to assure that the pressure vessels maintain integrity (e.g. do not leak) and thus can hold pressure/vacuum. Furthermore, energy requirements of pumps for evacuation and pressurizing the pressure vessels can be high and costly. U.S. Pat. No. 3,968,276 (Allen), U.S. Pat. No. 4,399,195 (Allen) and U.S. Pat. No. 4,433,031 (Allen) disclose wood treatment compositions and methods, and are incorporated herein by reference in their entirety.
With these requirements in mind, there is a need in the wood treatment industry for lower energy consumption methods and lower equipment and equipment maintenance costs for wood preservative applications.